A scroll is used in a compressor or the like configuring an air conditioning apparatus. This scroll has been manufactured mainly by casting, machining, or the like. In recent years, however, in order to increase productivity, strength or the like, scrolls are often manufactured by forging molding with the use of molds.
In a field of forging molding of an aluminum alloy, an iron alloy or the like, in order to reduce friction between a forging material and a mold, it is general to perform forging molding by interposing a lubricant between the forging material and the mold.
As the lubricant for forging molding, a graphite-based lubricant or a non-graphite-based lubricant is used.
The graphite-based lubricant has high lubricity at low cost, but the flash point of the base oil in which graphite is dispersed is 170° C. to 200° C., and therefore this lubricant has a danger of fire. Also, due to graphite contamination of the working environment there is a disadvantageous possibility of a health damage on human bodies.
By contrast, the non-graphite-based lubricant has a high flash point equal to or higher than approximately 270° C., and therefore a danger of fire is low. Since graphite is not used, safety of human bodies is high. However, the non-graphite lubricant has a problem of high cost and low lubricity compared with the graphite-based lubricant. When forging molding are performed by using a lubricant with low lubricity, the following three problems arise. Firstly, molding yields are decreased due to sticking to a mold or poor molding. Secondly, although a simple shape can be molded, it is difficult to mold a complex shape such as a scroll. Thirdly, the life of the mold is shortened.
Because of these problems, as a lubricant that can be used for forging molding, a lubricant for forging molding has been demanded, which is a safe non-graphite-based lubricant without graphite contamination of the working environment and has lubricity equivalent to or higher than that of a graphite-based lubricant.
Patent Document 1 discloses a non-graphite-based lubricant for a plunger-chip with improved lubricity, which is obtained by adding one or more types of oil, fatty acid, and fatty ester, a solid lubricant, and a surfactant to base oil made of mineral oil.
However, the lubricant disclosed in Patent Document 1 is a lubricant for casting and is not for forging molding, and no non-graphite-based lubricant having lubricity suitable for forging molding has been found yet now.